LENS: Light Transport

Z. W. Yokley, Virginia Tech On behalf of the

LENS Collaboration

The LENS Experiment

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• Neutrinos captured on 115In.

• Delayed gammas provide a triple coincidence.

• Beta decay of 115In is problematic ⇒ detector segmentation needed.

• See J9-5: LENS: Science Scope and Development Stages R. Bruce Vogelaar

• Low index barrier ⇒ total internal reflection (TIR)

2115115 eSnIne

The LENS Detector

Thin Container Filled with Liquid Scintillator, typical size of ≅8cm

Container Index of Refraction = n1 (Could be air)

Liquid Scintillator Index of Refraction = n2 > n1

The LENS Detector This is called a scintillation lattice (SL)

*Really this is a plane of a SL

Scintillation Lattice

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• See D14-6 LENS: µLENS Simulations, Analysis, and Results Charles Rasco

• Current development with single low index films.

– See J9-7: LENS: Prototyping Program S. Derek Rountree

The miniLENS Prototype

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• MiniLENS water tank for rock and PMT shielding.

– See the next talk : LENS: Prototyping Program

• Maintain channeling through shielding → use light guides (LGs).

MiniLENS LG Design

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1. Highly efficient for good energy resolution.

2. Low cost for material and labor.

3. High radiopurity and/or low mass to minimize background.

Construction and Testing of LGs

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• Built an LED+diffuser light source.

• Emission not isotropic ⇒ mapped emission distribution via masks on a bare PMT.

• Benchmark to ‘simple’ light guides

Construction and Testing of LGs

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• Tefzel and VM2000 were chosen for the initial tests.

• Tefzel film can be heat sealed to create a liquid tight barrier.

• Current tests– LGs sealed with clear water proof tape.

• Purely reflective LGs are made by rolling and taping long seam.

• Clear and multi film LGs can be made.

Construction and Testing of LGs

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Continued R&D

• Measured LG transport efficiency differ from the MC.

• Further work includes – New light source development.

– Further characterization of light source.

– Further MC benchmarking.

– Building and testing of multi-film LG for the miniLENS prototype.

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Source Distance (in)

Transport Efficiency

Monte Carlo MC:Data

5.0 72(3) 81.7(2) 1.13(5)

7.5 74(4) 83.7(3) 1.13(6)

Acknowledgements

• The LENS Collaboration – LSU: Jeff Blackmon, Charles Rasco, Liudmyla Afanasieva, Kevin Macon, Matt

Amrit

– Virginia Tech: R. Bruce Vogelaar, Mark Pitt, Camillo Mariani, S. Derek Rountree, Laszlo Papp, Zachary Yokley, Tristan Wright, Joey Heimburger, Lillie Robinson

– BNL: Minfang Yeh

– UNC: Art Champagne

– NCCU: Diane Markoff

– HBNI, India: Vivek Datar

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Extra Slides

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Scintillation Lattice

• LAB Scintillator in a Teflon Lattice

– Teflon: n1=1.34, LAB: n2= .53

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Single Element of Lattice Unit Sphere

Direction of Emitted Optical Photon originating from ANYWHERE in Cell

• The transport efficiency for LGs is the ratio of the light collected with the guide (B) to a bare PMT (A) where the collection distances (srcDis) are equal.

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LG Simulation and Benchmarking

• LGs are simulated using a simple ray tracing Monte Carlo (MC) program.

• LGs of varying shapes and constructions can be modeled.

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Some MC Results for LGs